SCIENCE FRIDAY: DAIRY MILK FOR ATHLETES - A PERFECT MIX OF AMINO ACIDS + CARBS FOR EXERCISE RECOVERY. IS A2 MILK AN ALTERNATIVE FOR THE INTOLERANT?
Scientists in the UK have provided information that may help athletes who are dairy intolerant take advantage of the post-exercise recovery benefits of cow’s milk ingestion! This blog discussion summarizes an article, ”A2 Milk Enhances Dynamic Muscle Function Following Repeated Sprint Exercise, a Possible Ergogenic Aid for A1-Protein Intolerant Athletes?” published by the journal Nutrients in January 2017:
Sport participation that requires strenuous physical activity with a large component of eccentric exercise, especially if unaccustomed, “often causes exercise-induced muscle damage (EIMD)”. Although exact mechanisms aren’t well understood, it’s thought that, as a result of multiple physiological changes in the muscle, function is compromised and muscle pain is evoked after such exercise.
Symptoms are known to peak at roughly 48 hours but can persist for 5-7 days. The occurrence and persistence can be detrimental in team sports, in which multiple competitions may occur during a weekly schedule and training must be resumed between competitive sessions.
Research has suggested protein-rich supplements (those with whey protein, casein protein, the amino acid leucine, or other branched chain amino acids) can reduced the unwanted effects of EIMD and speed recovery. Dairy milk beverages, with a combination of protein plus carbohydrate, and that have “favourable digestible and indispensable amino-acid score (DIAAS) >1.0, have been shown to expedite recovery.
The types of protein present in milk, slow-digesting casein (80%) and fast-digesting whey (20%) are though to deliver a balance of amino acids, especially the muscle-building branched chain amino acid leucine, to muscle such that signaling pathways are activated to speed synthetic processes and suppress breakdown.
Athletes with dairy intolerance aren’t able to take advantage of the properties of milk that may enhance recovery after strenuous exercise. It is generally considered that lactose malabsorption is the main culprit causing the symptoms of dairy intolerance. However, evidence suggests,indicates the article, that many who report gastrointestinal symptoms don’t lack the enzyme for lactose breakdown. More recently it has been postulated that a breakdown component (BCM-7) of casein present in regular milk but not in A2 milk may be responsible for causing “motility disorders, inflammation, abdominal pain and loose stools”, and that it may interact with lactose to worsen these issues.
The aim of this study was to investigate whether cow’s milk with A2 beta-casein protein was as effective as regular milk (which contains A1 and A2 casein) in lessening the effects of muscle damage when administered immediately after a specific, repeated, muscle-damaging sprint exercise. The hypothesis was that both milks would be equally effective, and that both milks would be more effective than a placebo drink (maltodextrin mixed with water).
Methods: 21 male athletes, average age 23 years, who were regular participants in team sports (7=Gaelic football, 7=soccer and 7= rugby) were randomly assigned to receive a supplement after muscle-damaging exercise (15 repetitions of a 30-meter sprint, with 60 second rest between each).
None had intolerance to lactose or dairy products. Seven were given regular milk, 7 consumed A-2 milk, and 7 took a placebo drink. Prior to and after exercise (at 24, 48, and 72 hours), each study participant was asked to rank muscle soreness (pain level while executing a squat at 90-degree knee flexion), and perform tests that would measure muscle function (maximal voluntary isometric contraction, countermovement jump [CMJ] height, and 20-meter sprint).
Regular and A-2 protein cow’s milk (500ml) supplements that were consumed immediately after the exercise session contained:
They conclude that study findings suggest “A2 milk might offer an alternative to athletes who experience GI [gastrointestinal] issues with regular milk” and that this possibility must be further investigated in those who are intolerant to A1 casein protein.
I recently became aware of A2 milk while reading a January 2018 Medscape.com article (reading it requires a free signup) "A2 Milk: Breakthrough of Science or Marketing?" It indicates, “we simply do not have the data right now to determine A2 milk’s benefits, or whether they even exist”.
A few other online articles have discussed this new trend with skepticism. Ally Gallop wrote a piece for the New England Dairy Council which offers a basic explanation of lactose intolerance, milk protein allergy, and dairy intolerance. Gallop cautions, “claims that A2 milk reduces dairy-related inflammation, heart disease, type 1 diabetes risk have not been supported by the science. The health benefits of A2 milk remain a theory, and more research is needed.” By the way, the “a2” brand is marketed by an Australian company. The gallon I purchased does not identify itself as organic.
Before rushing to switch from regular to the more expensive A2 milk, read a bit about it. There’s still a considerable amount of scientific investigation that will be required before that big question “Is it better for you than regular milk?” can be asked or answered.
The most important lesson to take from the EARNED RUNS BLOG post and the references: dairy milk is an ideal protein recovery food for strenuous post-exercise muscle maintenance, and source of calcium, fats, and other vitamins and minerals. In subsequent posts, we will hopefully examine the science that indicates dairy provides significant benefits when it comes to building and maintaining bone health for the BONE STRENGTH FOR ATHLETES page
Athletes who consider themselves milk intolerant and omit dairy from their diet may wish to test A2 milk.
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EARNED RUNS is edited and authored by me, runner and founder. I began participating in road races before 5Ks were common. I've been a dietitian, practiced and taught clinical pathology, and been involved with research that utilized pathology. I am fascinated with understanding the origins of disease as well as health.
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